Tannin is one of the three main flavours of a red wine, possibly the Holy Spirit of the wine trinity as it is the hardest to describe and control. It is present from fruit naturally, added through tea/tannin powder or passively from oak chips that simulate traditional barrel ageing.
Many think of tannin as something to be feared like a rabid dog, uncontrollable and aggressive ready to destroy everything it sees. In truth its more like an unruly puppy and with age and good rules you can tame it.
Tannin is a double edged sword (as well as a dog!?) as it can make a wine overly bitter or conversely give a complex deeper taste. The stronger the tannin the more it will dominate the sweetness present in the wine. Take this into account if aging for a year or more as the taste will change and tannins mellow. Tannin also creates “mouth feel” as it is the velvety (or gritty if you’re unlucky) texture on the tongue.
The first control is aging your wine. If a wine tastes too tannic there is no need to throw it out. Quite the reverse, leave it. Tannins bind as they age and settle as sediment, they bind forming chains that are too heave to be suspended and precipitate out. This is why a good wine often has sediment at the bottom of the bottle. Fruit wine like elderberry and oak leaf have naturally high levels of tannin due to their base fruit… and er leaf… so naturally they take longer to age. Elderberry at least a year or more compared to low tannin blackberries taking six to twelve months.
Another control is at the start of the wine making process. With berries pick your fruit in season when they are fully ripe to reduce the tannin content. This is something I find difficult imagining hordes of day trippers finding my foraging spots next to South Mims Services, picking all the best, mouths red with blackberry juice as they flick the V’s at me. Patience is a virtue and you will be aging a wine for a year so you can wait a fortnight before picking the fruit!
Tannin is not usually present in juice but is present in skins and harshest in seeds. Over squeezing elderberries can release too much tannin for light wines. Using a blender to whiz other fruit to a pulp will slice the seeds and release tannin. A blender has no use to a wine maker except slicing quince or menacing the cat.
The last control and most work is to take tannin into account when preparing the fruit. A cold soak uses aquious extraction to extend the flavour and colour extraction in water. This reduces the time the fruit stays in contact with an alcoholic extraction as it ferments as ethanol extracts tannin rather than water. Full details for COLD SOAK/MACERATION
High tannin levels are found in grapes, pomegranate, elderberries, blackcurrants and figs. Blackberries have a reasonable amount so no extra tannin is needed in a recipe but levels are low enough not to worry about over extraction.
Oak-leaf is the daddy – 50% of its dry weight is tannin. There is a simple extraction rule – leave to soak for 24 hours and no more! Simply pour over boiling water, cover and leave for a day before straining the water safely from the leaves. If you soak any longer you simply make a gallon of very strong tea. I hate tea. OAK LEAF WINE RECIPE